1. Field of the Invention
The present invention relates to a method of generating a writing pattern to write a mask pattern for use in immersion lithography, a method of forming a resist pattern by using immersion lithography, a method of controlling an exposure tool of immersion lithography type, and a method of manufacturing a semiconductor device.
2. Description of the Related Art
Development of an exposure tool has made a progress with pattern downsizing of a semiconductor device. As a next-generation lithography to 193 nm-“Dry”-lithography, a 157 nm-lithography has been developed. However the development of exposure tool and resist for 157 nm lithography is delayed. At this point in time, 193 nm immersion lithography attracts attention. In an immersion type exposure tool, a immersion medium fluid such as water has a greater refractive index than air is filled between an objective lens and a stacked resist films targeted for image focusing, thereby making it possible to increase a critical angle between the objective lens and the medium or between the medium and the stacked resist films. In addition, it is also possible to resolve a downsized pattern having a greater diffraction angle as an image by using a proper lens.
In 193 nm immersion lithography, the use of a pure water having a refractive index of 1.43 to 1.44 as the immersion medium fluid is discussed. In academy, there has been reported that water comes into contact with a stacked resist films, whereby a change relative to a resist shape occurs due to a change in composition distribution in a resist film caused by elution of a resist composition from among the resist film or water penetration into the resist film or the like. Specifically, a resist pattern is formed in a T-top shape. In order to solve this problem, there has been reported in the academy that a cover material film made of a resin is formed on the stacked resist films, thereby preventing elution of a photo acid generator (PAG) which is a resist composition, a photo generating acid, or a base into the water and infiltration of the water into a resist solvent. However, it is necessary to release the cover material film by using a special solvent as remover. Unlike a resist solvent generally used as the remover of cover material film, this special solvent is non-water soluble. Therefore, there is a need for a dedicated coating unit and/or a developing unit from the viewpoint of waste disposal. In a process for manufacturing a device such as a semiconductor, the use of the specific solvent results in a manufacturing cost. Thus, it is believed difficult to use the above cover material film of such type which requires a dedicated coating or developing unit. Therefore, it is desirable that an acid or alkali soluble cover material film exist which does not require a special remover unit. Further, it is more desirable that there exists a resist film material which does not require the cover material film, or alternatively, an additional resist process. In an acid or alkali soluble cover material film, it is an object to achieve the removeing by an acid or alkali soluble cover material film. Thus, water permeability is reliably lowered as compared with a cover material film requiring the special remover of cover material film. As a result, a certain counts of degree of immersion medium fluid penetrate into the inside of the resist film. Therefore, it is believed that there also occurs elution of the resist composition into water which is an immersion medium fluid.
As described above, in the case where a cover material film is not used from an aspect of a manufacturing cost in a lithography process using an immersion lithography device or in the case where a acid/base soluble cover material film is used, it is unavoidable to make a contact between the stacked resist films and the immersion medium fluid. According to patent document 1 and non-patent document 1, a practical immersion lithography tool has a function which selectively supplies an immersion medium fluid only onto stacked resist films in an exposure region (WO 99/49504; Soichi Owa and Hiroyuki Nagasaka, Immersion lithography; its potential performance and issues, Proc. of SPIE Vol. 5040, pp. 724 to 733).